Tunnel furnace



Patented Mar. 17, 1925.

UNITED STATES 1,529,755 PATENT OFFICE.

CHARLES M. STEIN, OF PARIS, FRANCE, ASSIGNOR TO SOCIETE ANONYIVIE DES I APPAREILS DE MANUTENTION ET FOURS STEIN, OF PARIS, FRANCE, A CORPORA- TION OF FRANCE.

TUNNEL FURNACE.

Application 'tiled August 19,1921. Serial` No. 493,599.

To all whom it may concern:

Be it known that I, CHARLES M. STEIN, a citizen of France, residing at Paris, France, have inventeda certain new and 5 useful Tunnel Furnace, of'wliich the following is a specification.

The invention relates to furnaces of the type wherein the .material to be heated, for example steel, brass, brick, etc., is moved l progressively through the furnace structure.

One object is to provide a furnace wherein the heatcontained in the heated material (after the latter has reached the desired temperature), is utilized efficiently to pre'- l heat the air supply, thus avoiding the necessity of employing regenerators or recuperators, in the ordinary meanings of the terms, in connection with the furnace.

- Preferably the air is led through the preheating chamber in such manner as to prolong its contact with the heated material and insure that only properly preheated air is withdrawn therefrom for combustion purposes; and the gases of combustion 'are led through and withdrawn from lthe heating chamber so as to bring about thorough contact with the material to be heated, and withdraw only such gases as have given up a maximum amount of their heat. Y

Another object is to construct the furnace in such manner that the air supply will be under proper control, both as regards quantity and temperature.

Another object is to rovide a. furnace justed to operate with fuels of different quality. p

Further objects and advantages of the invention will be in partv obvious and in part specically pointed out in the description hereinafter contained which, taken in connection .with the accompan ing drawings,

discloses a preferred embo iment thereof; such embodiment, however,.1s to be consid- 4 4 is a transverse section taken on which by simple manipu ations may be adered merely as illustrative of its principle.l

invc amber, taken on .line 3--3 of Fig. 1.. 'l 1g.

line 4 4 of Fig. 1, showing particularly the gas and air conduits employed in connection with the furnace.

Fig. 5 is a transverse sectional view showing the combustion chamber, taken on line The illustrated embodiment of the invention is designed particularly for use as an annealing furnace, and comprises an elongated heating chamber 1, having'a roof 2, and side walls 3, which may be of ordinary construction, the bottom of the chamber being provided with rails 4.- adapted to support cars 5 on to which the sheets to be annealed may be loaded, and thecars moved successively into the heating chamber 1 through a door 6 located at its entrance end.

At the delivery end `ofthe heating chamber 1 there is located a combustion chamber 7, in which a mixture of air and fuel is ignited and the products of combustion passed through the heatingchamber in a direction opposite'to the direction of travel of the cars therethrough, and are intimately brought into contact with the material to be heated to raise the temperature of the latter to the desired point.

In order to provide a supply of preheated air to the combustion chamber without necessitating the employment of a recuperator or regenerator of -ordinary form, the air which is to support'combustion is led past thecars 5 after the material carried by the latter has been raised to the desiredtemperature. This step of preheating the air is carred out in a preheating chamber 8 which conveniently may be placed end to end with the heating chamber 1, and the rails 4 are led` through the preheating chamber 8, in such manner that the cars 5 may travel from the delivery end of heating chamber 1 through a doorway 9 into the preheating chamber 8,

and pass out through a door or the like 10 at the .end of the preheating chamber.

Awith fuelto be burned in the combustion 'chamber 7. As shown in Fig. 1, I prefer to lead the cold air into the preheating chamber 8" adjacent the bottom of the chamber at its ldelivery end, and to 'withdraw the prehe'ated air by means of one or more air conduits 13 located adjacent the upper portion ofthe entrance end of thepreheating" heating chamber, and the heated air will rise n to the top of the chamber and pass out l through conduits 13, whereas the air which has not been properly preheated will remain in further contactlwith cars 5 carrying the heated materia-l minimizing. the liability of cool air passing from the intake passageway 11 out through conduits 13 without proper preheating.

In order to control the amount of air passing through the furnace, I prefer to introduce the air through passageway 11 under pressure, from a blower 12 or the like, and dempers 15 (Fig.` are associated with the air conduits 13 to permit the rate of flow of the air to be adjusted. Thus the amount` of air fed to the furnace may be regulated as desired and also the speed at which it passes through the preheating chamber 8, whereby the desired temperature` of the air may be obtained, as well as the desired quantity.

As'shown in Fig. 4, it is preferred to employ two air conduits 13 issuing from opposite sides of the preheating chamber' 3, thus balancing the 4flow of air through the pre.- heating chamber tothe' combustion chamber 7. l/Vh'en the furnace is operating with lean fuel such as producer gas, the gas may be lead in through intake gas conduits 16 (F ig. 4) connecting into ports 17 (Fig. 5) associated with the ports 14. The furnace, however, may be readily shifted to operate with.

richer fuels such as coke oven gas or oil, by adjusting dampers 18 (Fig. 5) to close gas ports 17, and opening the supply pipes 19 which connect with fuel ports 20, adapted to project the rich gas laterally into the combustion chamber above lthe material to i' be heated and in the path of the air issuing from-the ports 1 4.

I prefer to locate the combustion cha-1nber 7 at the upper portion of heating chamber 1, vso that the flames may play downwardly over the material carried by the adjacent truck A baffle 21 (Figs. 1 and 5) may also be employed, projecting downwardly from the top wall 2 of 'chamber 1 so as to confine the flames and insure that the products of combustion pass downwardly into thorough Contact with the material to be heated instead of escaping along the top portion 4of the combustion chamber.` Further, II prefer to withdraw the products of combustion from the lower portion ofthe ,entrance endv of heating chamber 1, as by one or more exhaust fines 22; only such gases will sink to the bottom of the heating g j f 1,529,755

chamber as have given up a maximum amountof their heat to the material carried by cars 5, thus the best etficienc of heat exchange is secured by leading tie spent gases of combustion through and outof the heating chamber in this manner.

In the operation of the furnace, communication vbetween the preheating chamber 8 and the heating chamber 1 is first shut olf by means of a removable door 22 interposed between the. same, the door being madeas air-tight as possible in order to prevent a direct passage of air between the chambers without passing through the air conduits 13. The air is forced through the preheating chamber S by the blower ,12, and the quantity of air so fed may be controlled by adjustment of the blower. The cold air is directed through the intake passageway 11 into the lower portion lof the preheating chamber at its delivery end, and passes through the chamberinto contact with the fully heated material carried by the cars `5 which are within the preheating chamber; as the air becomes preheated, it rises and is assisted by natural draft in passing out through air conduits 13 to the combustion chamber; thus with the air conduits 13 located at the upper portion of the preheating chamber, it is insured that onlyproperly preheated air will be withdrawn from the chamber, and less air pressure is required to force the preheated air through conduits 13, and consequently the tendency of the air to leak past door 22 is decreased.

As appears from Figs. 2 and 3 'the cross section ofthe preheating chamber 8 is preferably made larger than that of heating chamber 1 and thus the velocity of travel of the air through the preheating chamber is less than that of the burned gases through velocity, and thus by means of the blower 12 and the damper both the quantity of air and its temperature may be varied to meet the conditions of operation of the furnace.

The mixture of air and fuel is ignited in the combustion chamber 7, and the Haines pass downwardly-into contact with the material carried, so that the adjacent truck 5 and baille v21 serve to force the flames to pass into .close-contactwith such. material. The burned gases then pass' through. heatin chamber 1 into contact with the materia carried by all the cars- 5 contained Within such chamber, and at the entrance end there.-l

vof the heating'chamber into the entrance end of the preheating chamber, and ejecting the car which previously 4was a-t the delivery end of the prelieating chamber, and which had given up as muchheat as possible to the incoming air. The doors 6, and 22 are then moved to closed position and the operation of the furnace is repeated as above described.

iVliile a specific embodiment of the invention has been described, it is obvious that many changes may be made therein without departing from the spirit of the invention as defined in the following claims.

l. The method of operating a tunnel furnace which comprises conducting a gaseous current, which is to enter into combustion, past the heated material to preheat the gaseous current, forming a, combustible mixture including said gaseous current, ignitiiigthe mixture, and' passing the products of combustion along the material .to be heated at a relatively higher velocity than that at which the gaseous current moves past the heated material.

2. The method of operating a tunnel furnace having an air preheating chamber and a heating chamber, which comprises moving the heated material from the heating chamber into the preheating chamber, passing substantially all the air required `for combustion at a relatively low velocity through said preheating chamberxinixing the preheated 4air with`fuel, ignitiiig the mixture, and passing the products of combustion through the heating chamber at a relatively higher velocity.

The method of operating a tunnel furnace having an air prelieating chamber and a heating chamber, which comprises moving the heated material from the heating chamber into the preheating chamber. passing air into the lower portion of said preheating chamber, and withdrawing the preheated air from the upper portion of said chamber, mixing the air with fuel, igniting the mixture adjacent the upper portion of the heat ing chamber, and withdrawing the same from the lower portion of said heating chamber.

4. A tunnel furnace having an air preheating chamber and a heating chamber, removable means vfor shutting off communication between Said chambers, and a conduit for preheating air leading from the upper portion of said preheating chamber to the upper portion of said heating chamber.

5. A tunnel furnace havingan air pre,- heatingchamber and a heating chamber, removable means for shutting ofi' communcation between said chambers, means for forcing air under pressure into said prehe'atin'g chamber, and a preheatedair conduit eX- tending between said preheating chamber and the upper portion of said heating chamber. y

` 6. A tunnel furnace having Ian air preheating chamber anda heating chamber, means whereby material to be heated may be introduced into said heating chamber and withdrawnY from saidfpreheating chamber, an air intake passageway connected to said preheating chamber, and a waste gas Hue leading from said heating chamber, said pre- -heating chamber being of larger effective cross section than said heating chamber.

7. A tunnel furnace having an air preheating chamber and a heating chamber, means whereby material to be heated may be introduced into said heating chamber and withdrawn from said preheating chamber, inca-ns for forcing air under pressure into said preheating chamber, a conduit for preheated air leading from said preheating chamber to said heating chamber, and a damper associated with said preheated air conduit.

8. A tunnel furnace having an air preheating chamber, preheated air conduits leading from the upper portion of the preheating chamber on opposite sides thereof, a heating chamber. having a combustion chamber adjacent the upper portion thereof. said air conduits leading to air ports iii said combustion chambei, and removable means for shutting offcommunication be tween said chambers.

9. A tunnel4 furnace. a heating chamber having a combustion chamber adjacent the upper portion thereof. an air preheating chamber, preheated air conduits leading Jfrom' the upper portion of the preheatiiig chamber on opposite sides thereof and connectcd to ports which open into said combustion chamber. and sets of rich and leaii fuel ports associated respectively with said air ports.

In testimony that I claim the foregoing. I have hereunto set my hand this 12 day of July, 1921.

CHARLES M. STEIN. 

